Amtrak and MARC train service that was disrupted yesterday when a ruptured water main flooded tracks between Washington and Baltimore is expected to resume this morning with a few cancellations and some delays, transit officials said.

Trains are likely to be delayed 10 to 20 minutes between Washington and Baltimore because of speed restrictions prompted by track repairs in the Halethorpe area of Baltimore County, said Amtrak spokeswoman Karina Romero. She said a "minimal" number of Amtrak trains will be canceled until those stranded yesterday can be returned to the cities where they originate.

"It will definitely be an improvement from today, but we will not be back to normal," Romero said yesterday evening. Amtrak said thousands of passengers were delayed yesterday.

Today, southbound Acela Express trains will not stop at Baltimore-Washington International Thurgood Marshall Airport until the repairs are completed, Romero said. Delays on Amtrak's busy eastern corridor could occur as far north as Boston, she said.

She said passengers traveling between Washington and points north should call 800-USA-RAIL (800-872-7245) to confirm train times. Service between Washington and points south will not be affected, she said.

All MARC trains on the Penn Line were scheduled to run this morning, said MARC spokeswoman Cheron Wicker. But 20-minute delays caused by track work between Odenton and Baltimore's Penn Station could extend into the afternoon, she said.

Trees, mud and other debris from the water main break damaged tracks in Halethorpe, near Interstate 95 and between I-195 and I-695, shortly before dawn yesterday, transit officials said.

The 36-inch concrete main, buried adjacent to the tracks, is a major line connecting much of Howard County and a Baltimore water treatment plant, said Kurt Kocher, a spokesman for the Baltimore City Department of Public Works.

He said water pressure should be restored throughout Howard by this morning. Howard residents and businesses were asked to conserve water overnight to help storage tanks refill more quickly. The cause of the break was not immediately known, he said.